Early brain insult and cognition: a comparison of malnutrition and hypothyroidism

The effects of two biological insults, hypothyroidism and malnutrition, incurred during pre- and postnatal development were compared using a newly developed test of observational learning in rats. Whereas early hypothyroidism produced a significant impairment in observational learning in recovered rats, no indication of any impairment was observed in rats recovered from early malnutrition. These results are important in that they demonstrate that tests of advantageous learning such as observational learning are sensitive to the kinds of early biological insult that lead to permanent cognitive impairment in humans. Moreover, these data further support the concept that the cognitive impairment observed during periods of malnutrition in humans and animals is not permanent.